Today a wide variety of industries use stainless steel beams. Their strength, toughness and high corrosion resistance make them ideal for structural applications in harsh or corrosive environments.
Stainless Steel Beams – Standard Structural Shapes
There is a huge variety of different stainless steel beam sizes, which can be sourced throughout the world. Engineering standards define the different types and sizes of stainless steel structurals. For example, in Europe, there are the European Norms (EN), in America the ASTM standards and in Japan the JIS regulations. Stainless steel structurals stand for a big product family, which encompasses stainless steel profiles like equal and unequal angle bars, stainless steel channels, tees and last but not least stainless steel beams. Some of these standard profile catagories have further subcategories. This essay focusses on stainless steel beams, as they represent an important product group among the ones mentioned above.
European Stainless Steel Beams
IPE stainless steel beams, also known as “I-sections”, are named after their most obvious characteristic – the ‘I’ shape. The I-beam is the universal and most common profile in the family of stainless steel beams. Generally, these beams have double the height when you compare it to their flange width.
IPN stainless steel beams, another I shaped profile, have conical or slightly sloped flanges, compared to the flat and 90 degrees flanges of the IPE beams. Their size range is very similar to the IPE beams. The conical flanges make it less user-friendly for certain structural applications. For example, bolting the flanges together requires special conical washers. For this reason, the IPN is losing importance towards the IPE beams.
There are three types of H stainless steel beams, which are subclassified into light, intermediate and heavy H beams, respectively codified as HEA, HEB and HEM. H-beams have a higher moment of inertia compared to the slender I-beams. Due to their enlarged flange width and thickness, they are “stronger” than I-beams with equal heights and can carry much higher loads and pressure.
Besides these continental European stainless steel beam types, there are also country specific types like the British Universal Columns and Universal Beams.
American Stainless Steel Beams
S-beams are the American counterparts of the European IPN beams. The stainless steel S-beams have conical flanges. It is a very common American beam type for construction in corrosive environments.
W-beams, also known as wide flange beams, are the American counterparts of the European H-beams. They have been designed for heavy loads and find applications where the structural properties of S-beams will not reach the demanded values.
Production Methods of Stainless Steel Beams
Hot Rolling of Stainless Steel Beams
As for all structural steel shapes, the most cost efficient production technology for stainless steel beams is hot rolling as well. Unfortunately, there is a technical limitation: hot rolling requires sufficient volumes to justify a rolling campaign. However, today the worldwide annual consumption does not reach the minimum quantity for all beam types and sizes.Hence, there are only few sizes of stainless steel beams that rolling mills do hot roll. The standard of the bars’ length for stainless steel section is six meters (20 feet) and customized lengths cannot be considered at all.
Hot Extruding of Stainless Steel Beams
Another production technology for stainless steel beams is hot steel extrusion. Hot extrusion of stainless steel beams does not demand for minimum quantities, also small batches of only a few bars are possible. Beams with conical flanges can be hot extruded easily. The downside of hot extrusion is the limited size range, which encompasses beams up to 150 millimeters and less accurate dimensional tolerances. In the smaller size range, the standards define material thicknesses of four to six millimeters. The extruded stainless steel beams require a bigger thickness there, increasing overall weight and loosing compliance to the standards.
Bolting of Stainless Steel Beams
Another way to realize stainless steel beams was bolting together two stainless steel channels, either hot rolled or by press brake. This was common practice in the past, but lost importance due to global availability of stainless steel beams. Nowadays, this solution is rarely used and not allowed for many applications.
A much more common production method, probably the most popular, is welding. There are different types of welding that give different results.
MAG Welding of Stainless Steel Beams
Welding is a production method that brings an important amount of heat into the material. Unlike carbon steel, stainless steel is much more prone to distortion and deformation when heated up during the welding process.
As a result, small size stainless steel beams cannot be properly welded by using conventional welding methods like TIG/MAG or plasma welding. The heat input deforms the built up beams so much, that straightening becomes impossible.
Larger stainless steel beams are normally MAG fillet welded. In order to compensate distortion of the flanges, generally they are pre-bend to the opposite direction, so that the weld heat “pulls” them into a flush position.
Laser Welding of Stainless Steel Beams
Another welding method, that does not bring up these big issues with straightening due to heat input, is laser welding.
Laser welding technology allows non-restrictive production of stainless steel beams from small to medium and large size beams. Likewise, for conventional welding and hot extrusion, there are no minimum runs; one single bar is feasible. Laser welding melts web and flanges together without additional filler metal. The distortion is strongly reduced, as the heat is limited to a little area called “plasma pool”. As stainless steel sheets are the raw material base for built-up beams, there is a great flexibility as far as special length is concerned.
| Production method | Cost | Productivity | Availability | Min. quantity | Quality |
|---|---|---|---|---|---|
| Hot rolling | Low | High | Limited | Yes | Good |
| Hot extrusion | Average | Medium | Good | No | Good |
| Bolting | Low | Low | Good | No | Low |
| MAG welding | Average | Low | Good | No | Low |
| Laser welding | Average | Medium | Good | No | Excellent |
Standard Grades for Stainless Steel Beams
Beams are commonly available in the following stainless steel grades: 1.4301 (304) or its low carbon version 1.4307 (304L), 1.4401 (316) respectively 1.4404 (316L) and the German variant 1.4571 (316Ti).
304/L is the main choice for average corrosive environments. 316/L on the other hand will be the selected material for a higher level of corrosion or also acid resistance. Therefore, you can find it especially at the seaside, in strongly polluted environment or in the chemical industry. For these standard material grades, stainless steel beams generally can be sourced off-the-shelf.
Stainless Steel Beams in Special Materials
Sometimes the standard corrosion resistant properties or the mechanical properties of the common grades are not sufficient. So for more demanding structural applications, beams in different materials will be produced. It is possible to produce beams in material grades like high temperature resisting stainless steels, duplex stainless steel and super austenitic stainless steels. It is also possible to produce beams in certain grades of ferritic stainless steel. Martensitic stainless steel is not possible. In case the production method is welding – both TIG-MAG and laser welding – so called black and white combinations are possible. It happens that one part of the beam is bedded in concrete and only one flange is exposed and must be corrosion resistant. With the welding technology, it is possible to produce breams having each single component (web and each flanges) made of a different material.
Stainless Steel Beams in Everyday Life
Thanks to its properties, stainless steel is often a preferred choice for a vast range of applications.
A lot of industrial sectors – especially the chemical, petrochemical, offshore , pharmaceutical, medical, food processing and beverage industries – use stainless steel. A large consumption is for stainless steel pipes or tubes that convey all kinds of liquids and gases. These pipes generally require supports or pipe racks, which are often made with stainless steel beams.
Stainless steel beams can be sterilized and sanitized. That also makes them an ideal material for the food processing and pharmaceutical industry, where all kinds of conveyors are used.
Another typical application for stainless steel beams is in architecture. Stainless steel is used more and more for urban furniture and architecturally exposed stainless steel (AESS) structures. There are mainly three reasons for it: long lasting, aesthetically pleasing thanks to various surface finishes and almost zero maintenance. Carbon steel on the other hand must be painted or coated regularly.
Stainless Steel Structures and Canopies
Stainless steel firstly made its entrance in construction during the Art Deco period. For instance, the upper part of the Chrysler Building was erected using stainless steel.
Stainless steel features prominently in high-end contemporary architecture like for example the Helix Bridge in Singapore and the New Zollhof (Neuer Zollhof) in Duesseldorf, Germany using stainless steel profiles for structural purposes and metal sheets for decorative cladding of the building’s exterior.
Canopies are also often made from stainless steel sections. These may be standard structural sections like stainless steel beams or tees, but increasingly architects like to design and combine these projects with sharp edged stainless steel hollow sections or other special shapes, like the Cross Rail Access at London’s Paddington Train Station.
Throughout the world, structural stainless steel sections are used in buildings, generally as mullions and transoms in steel glass facades. There, stainless steel beams carry the load of large glazing panels becoming an eye-catching element in the main entrance or lobby of the building. A stainless steel mullion allows significantly greater heights and wider spans compared to conventional aluminum sections.
Stainless Steel – Best in All Weathers
Stainless steel offers great solutions for all weathers. Depending on the application and environment, stainless steel beams offer various advantages compared to other structural materials like carbon steel and aluminum.
On top of this list, there is the well-known corrosion resistance of stainless steel beams and their ability to cope with hot, salty, humid or polluted environments. Stainless steel beams are also used for cryogenic applications like for example LNG application and its regasification plants. Stainless steel beams expand thermally much less compared to aluminum, thus their use i.e. in curtain walls is preferred, as no thermal expansion joints must be planned.
In addition, the chemical, oil and gas industries operate in demanding environments involving high heat and highly toxic substances. Special grades of stainless steel have been developed for use in these industries. They feature enhanced resistance to corrosion over a wider range of temperatures. High-grade stainless steel is vital in the construction of storage tanks, valves, pipes, pipe racks and other components.
Applications with Stainless Steel Beams
Tanks and Vessels
A very common application is the tank and vessel construction. The various duplex stainless steel grades (from lean duplex over standard to super duplex) are often used due to their high strength and high corrosion resistance.
Duplex stainless steel can be produced in large sheets, which minimizes welding and maximizes structural integrity. Its higher strength also reduces the need for extra structural support and foundations, reducing construction costs. In these cases, the tank may be designed without stiffening beams, while the duplex stainless steel beams will generally only be used for the dome that closes the tank.
Offshore Oil Rigs
Stainless steel is essential for offshore oil rigs. This is due to the fact, that seawater and especially crude oil are extremely corrosive and modern rigs are constructed from high-alloyed steel, which is tough and lightweight.
Renewable Energy
Renewable energy technologies including solar, geothermal, hydro and wind power also use stainless steel components, as it is able to withstand the rigors of highly corrosive environments.
Beams made in special stainless steel grades like for instance 1.4912 (347H) grant corrosion resistance in tanks for hot brine used in solar power plants and are suitable to resist the extreme environment, as the nights in the desert are very cold.